Empty Fruit Bunch Boiler is full name of EFB Boiler. Oil palm is an industrial crop with high utilization value in Thailand, Malaysia, Indonesia and other Southeast Asian countries. Palm oil is not only a high-quality edible oil, but also a biomass energy used as a substitute for diesel. Therefore, development of new environmentally friendly biomass boiler to deal with EFB can obtain good economic and social benefits. Empty Fruit Bunch Boiler has huge market demand.
I. Empty fruit bunch research analysis
- Elemental analysis, industrial analysis and calorific value test
EFB fuel features high oxygen, volatile, ash, sulfur and nitrogen content. Overall, the fuel meets the characteristics of typical biomass fuel. Original EFB fuel contains about 50% moisture, thus the calorific value is low. Net caloric value of as-received basis is only 7661kJ/kg.
- Alkali metal content
Active inorganic impurities like potassium and chlorine are the core inducing factors of coking, slagging and high temperature corrosion. The sodium content in EFB is low, but potassium is close to 1.95%. In addition, it also contains a higher chlorine, which will further promote the precipitation and conversion of potassium. Pay much attention to the flue gas temperature at the entrance of high temperature convection heating surface, lateral pitch of tube bundle, and control of superheater wall temperature.
- Ash melting point
The test deformation temperature of EFB ash is 820℃, which is a low-melting solid fuel. The temperature difference of each characteristic is very small. The ash will rapidly melt after the ambient temperature is above a certain point.
- Composition analysis of ash
The ash component at 600℃ and 700℃ are similar, the content of K and Cl has little difference. However, ash composition changes after the temperature exceeds 800℃, especially 900℃. The content of K and Cl decreases, while the content of Si, Ca, Fe, S and Al increases.
II. Empty Fruit Bunch Boiler Design Guide
- Actual moisture is around 52-53%, while moisture content is of huge influence on fuel ignition and combustion design. We shall get accurate water content of EFB under large-scale utilization condition, and design the Empty Fruit Bunch Boiler accordingly.
- The K and Cl content of EFB are 1.95% and 0.466% respectively. We shall control the wall temperature of high-temperature heating surface, increase the wall thickness, and select proper pipe material to mitigate the risk of corrosion and tube explosion.
- Empty Fruit Bunch Boiler design shall pay full attention to the furnace outlet temperature and high-temperature superheater inlet temperature. The pitch of high-temperature convection heating surface shall be big enough to avoid ash accumulation and clogging.
